Liquid crystal display apparatus which performs display by using electric field in direction substantially parallel with substrate surfaces to control alignment direction of liquid crystal molecules

ABSTRACT

A liquid crystal display apparatus includes a liquid crystal layer which is disposed in a gap between first and second substrates with long axes of liquid crystal molecules being aligned in one direction, in substantially parallel to substrate surfaces. A plurality of thin film transistors are arranged in row and column directions on an upper side of the first substrate. Pixel electrodes are provided on the upper side of the first substrate to be electrically connected with the thin film transistors. A common electrode is formed on the upper side of the first substrate between the substrate and the liquid crystal layer to correspond to the pixel electrode through an insulating film, and generates an electric filed which controls an alignment direction of the liquid crystal molecules in a plane substantially parallel with the substrate surfaces between itself and the pixel electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional Application of U.S. applicationSer. No. 11/412,037 filed Apr. 26, 2006 now U.S. Pat. No. 7,619,698,which is based upon and claims the benefit of priority from priorJapanese Patent Application No. 2006-022438, filed Jan. 31, 2006, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display apparatuswhich performs display by using an electric field parallel withsubstrate surfaces to control a direction of liquid crystal molecules ina plane parallel with the substrate surfaces.

2. Description of the Related Art

As a liquid crystal display apparatus, there is known one having aconfiguration in which a liquid crystal layer having liquid crystalmolecules aligned in substantially parallel with substrate surfaces withlong axes being aligned in one direction is provided between a pair ofsubstrates facing each other with a gap therebetween. Pixel electrodesand a common electrode which are insulated from each other are providedon an inner surfaces of one of the substrates facing each other in orderto generate an electric field which controls an alignment direction ofthe liquid crystal molecules in a plane substantially parallel with thesubstrate surfaces.

Conventionally, this liquid crystal display apparatus is configured toinclude on an inner surface of one of the substrates, a common electrodecorresponding to each pixel region, and a plurality of pixel electrodesprovided on an insulating layer covering the common electrode inaccordance with the common electrode. A plurality of thin filmtransistors respectively are connected with these pixel electrodes also,there are provided a plurality of scanning lines which supply gatesignals to the thin film transistors in respective rows, and a pluralityof signal liens which supply data signals to the thin film transistorsin respective columns, such an apparatus is described in, for example,Jpn. Pat. Appln. KOKAI Publication No. 2002-82357.

In the conventional liquid crystal display apparatus, alignment ofliquid crystal molecules in a peripheral region of each pixel isdisordered, light leaks in a peripheral portion of the pixel and thuscontrast is lowered, due to an influence of an electric field generatedbetween the scanning lines or the signal lines and the pixel electrodes.Further, when a black mask is provided in order to avoid this lightleak, there occurs a problem that an aperture ratio is reduced and adisplay image is darkened.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a liquid crystaldisplay apparatus which can eliminate light leak in a peripheral portionof each pixel and increase contrast and an aperture ratio to display abright image.

According to a first aspect of the present invention, there is provideda liquid crystal display apparatus a liquid crystal display apparatuscomprising:

a pair of substrates arranged to face each other with a gaptherebetween;

a liquid crystal layer which is disposed in the gap between the pair ofsubstrates with long axes of liquid crystal molecules being aligned inone direction, in substantially parallel to substrate surfaces;

a plurality of thin film transistors which are arranged in a rowdirection and a column direction on an inner surface side of one of thepair of substrates that faces the other substrate, and to which displaysignals corresponding to display data are supplied;

a plurality of pixel electrodes which are provided on the inner surfaceside of the one substrate to be electrically connected with the thinfilm transistors, and to which the display signals are supplied from thethin film transistors; and

a common electrode which is formed on the inner surface side of the onesubstrate between the one substrate and the liquid crystal layer tocorrespond to the pixel electrode through an insulating film, andgenerates an electric filed which controls an alignment direction of theliquid crystal molecules in a plane substantially parallel with thesubstrate surfaces between itself and the pixel electrode.

In this liquid crystal display apparatus, it is desirable that at leasta part of the common electrode is superimposed on the pixel electrodeand at least one edge portion which defines each pixel is formed inaccordance with each region corresponding to the pixel electrode.Furthermore, it is desirable that an edge portion which defines eachpixel in accordance with each region corresponding to the pixelelectrode and a plurality of edge portions arranged on an inner side ofthe pixel region are formed between the common electrode and the pixelelectrode in order to generate an electric field in a directionsubstantially parallel with the substrate inner surfaces.

In this liquid crystal display apparatus, it is desirable to furtherprovide on an inner surface side of one of the substrates: a pluralityof scanning lines which are respectively arranged along a row directionbetween rows of the respective pixel electrodes and supply scanningsignals to the thin film transistors in the respective rows; and aplurality of signal lines which are respectively arranged along a columndirection between columns of the respective pixel electrodes and supplydisplay signals to the thin film transistors in the respective columns.

Moreover, it is desirable that the common electrode is formed into acontinuous shape extending in at least one of the pixel electrode rowdirection and the pixel electrode column direction on an insulatinglayer covering the plurality of pixel electrodes, thin film transistors,scanning lines and signal lines by a region covering at least one of aregion between the pixel electrodes adjacent to each other with thescanning line therebetween and a region between the pixel electrodesadjacent to each other with the signal line therebetween, a plurality ofpartial electrodes which are aligned in parallel with each other atintervals are formed at a part of the common electrode corresponding tothe pixel electrodes, and an electric field which controls an alignmentdirection of the liquid crystal molecules is generated between an edgeportion of each partial electrode and the pixel electrode.

Additionally, in this liquid crystal display apparatus, it is desirablethat the insulating film which is interposed between the pixelelectrodes and the common electrode of one of the substrates is aflattened film which is formed to cover the pixel electrodes, the thinfilm transistors and wiring lines connected with the transistors anddetermines an inner surface of one of the substrates as a flat surface.

In this liquid crystal display apparatus, it is preferable to furtherprovide on the inner surface of one of the substrates: a plurality ofscanning lines which are respectively arranged along a row directionbetween rows of the respective pixel electrodes and supply scanningsignals to the thin film transistors in the respective rows; and aplurality of signal lines which are respectively arranged along a columndirection between columns of the respective pixel electrodes and supplydisplay signals to the thin film transistors in the respective columns.

Further, it is preferable that the common electrode is formed on aninsulating layer covering the plurality of pixel electrodes, thin filmtransistors, scanning lines and signal lines to cover both a regionbetween the pixel electrodes adjacent to each other with the scanningline therebetween and a region between the pixel electrodes adjacent toeach other with the signal line therebetween, a plurality of edgeportions which are aligned in parallel with each other at intervals areformed in a region of the common electrode corresponding to the pixelelectrode, and an electric field which controls an alignment directionof the liquid crystal molecules is generated between the edge portionsand the pixel electrode.

In this case, it is preferable that, on an insulating film of onesubstrate, the common electrode is constituted of a transparentelectroconductive film in which a plurality of edge portions aligned inparallel with each other at intervals in a region corresponding to eachpixel are formed, and a metal electroconductive film formed along one ofa scanning line extending along a row direction between the pixelsadjacent to each other and a signal line extending in a column directionbetween the same. Furthermore, it is preferable that, on the insulatingfilm of the one substrate, the common electrode is constituted of atransparent electroconductive film in which a plurality of edge portionsaligned in parallel with each other at intervals in a regioncorresponding to each pixel are formed; and a metal electroconductivefilm which is formed along at least a scanning line of the scanning lineextending in a row direction between the pixels adjacent to each otherand a signal line extending in a column direction between the same tocover the scanning line and the thin film transistor. Moreover, it ispreferable that, on the insulating film of the one substrate, the commonelectrode is constituted of a transparent electroconductive film inwhich a plurality of edge portions which are aligned in parallel witheach other at intervals in a region corresponding to each pixel areformed, and a metal electroconductive film which is formed along atleast a scanning line of the scanning line extending in a row directionbetween the pixels adjacent to each other and a signal line extending ina column direction between the same at a part excluding a regioncorresponding to the thin film transistor to cover the scanning line.Additionally, in this case, it is desirable to further include a lightshielding film which is formed on an inner surface of the other one ofthe pair of substrates in a region corresponding to each thin filmtransistor formed on the one substrate. Further, it is preferable that,on the insulating film of the one substrate, the common electrode isconstituted of a transparent electroconductive film in which a pluralityof edge portions aligned in parallel with each other at intervals in aregion corresponding to each pixel are formed, and a metalelectroconductive film formed along both a scanning line extending in arow direction between the pixels adjacent to each other and a signalline extending in a column direction between the same.

In this liquid crystal display apparatus, it is preferable that thecommon electrode is formed on a substantially entire surface of theinsulating film covering the plurality of pixel electrodes, thin filmtransistors, scanning lines and signal lines, and slits which generatean electric field which controls an alignment direction of the liquidcrystal molecules between the common electrode and the pixel electrodesand form a plurality of edge portions aligned in parallel with eachother at intervals are provided in a region of the common electrodecorresponding to each pixel electrode. In this case, it is preferablethat the slits formed in the common electrode are formed toward adirection obliquely crossing a direction of an aligning treatment of analigning film to form edge portions which cross in an oblique stateexcept perpendicular and parallel states a direction of long axes of theliquid crystal molecules aligned by the aligning film formed on onesubstrate surface. Furthermore, it is preferable for the pixel electrodeformed on the one substrate to be constituted of a transparentelectroconductive film which has a shape corresponding to the slitsformed in the common electrode in a region corresponding to the pixeland has opening portions formed in a region overlapping the slits of thecommon electrode. Moreover, it is desirable for the pixel electrodeformed on the one substrate to be constituted of a transparentelectroconductive film which has a shape corresponding to the slitsformed in the common electrode in a region corresponding to the pixeland has an opening portions formed in a region overlapping the slits ofthe common electrode.

In this liquid crystal display apparatus, it is preferable for the pixelelectrode formed on the one substrate to be constituted of onesubstantially rectangular transparent electroconductive film having anarea corresponding to the pixel.

According to a second aspect of the present invention, there is provideda liquid crystal display apparatus a liquid crystal display apparatuscomprising:

first and second substrates arranged to face each other with a gaptherebetween;

a liquid crystal layer which is disposed in the gap between the pair ofsubstrates with long axes of liquid crystal molecules being aligned inone direction, in substantially parallel with substrate surfaces;

a plurality of thin film transistors which are arranged in a rowdirection and a column direction on an inner surface side of the firstsubstrates that faces the second substrate, and to which display signalscorresponding to display data are supplied;

a plurality of pixel electrodes which are provided on the inner surfaceside of the first substrate to be electrically connected with the thinfilm transistors, and to which the display signals are supplied from thethin film transistors;

a plurality of signal lines which are respectively arranged betweenrespective pixel electrode rows along the row direction on the innersurface side of the first substrate and which supply scanning signals tothe thin film transistors in the respective rows;

a plurality of signal lines which are respectively arranged betweenrespective pixel electrode columns along the column direction on theinner surface side of the first substrate and which supply displaysignals to the thin film transistors in the respective columns; and

a common electrode which is formed on an insulating film on the innersurface side of the first substrate to correspond to the pixelelectrodes between the pixel electrodes and the liquid crystal layer,and the common electrode being constituted of a transparentelectroconductive film in which a plurality of edge portions aligned inparallel with each other at intervals in a region corresponding to eachpixel are formed, and of a metal electroconductive film which is formedalong at least the scanning line of the scanning line extending in therow direction between the pixels adjacent to each other and the scanningline extending in the column direction between the same to cover thescanning line and the thin film transistor, wherein the common electrodegenerates an electric field which controls an alignment direction of theliquid crystal molecules in a plane substantially parallel with thesubstrate surfaces between itself and the pixel electrode.

In this liquid crystal display apparatus, it is preferable that thecommon electrode is formed on a substantially entire surface of aninsulating layer covering the plurality of pixel electrodes, thin filmtransistors, scanning lines and signal lines, slits forming a pluralityof edge portions aligned in parallel with each other at intervals togenerate an electric filed which controls an alignment direction of theliquid crystal molecules between the common electrode and the pixelelectrode are provided in a region of the common electrode correspondingto the pixel electrode, and the common electrode is bent in a V-likeshape to form an edge portion which crosses in an oblique state exceptperpendicular and parallel states a direction of an aligning treatmentof an aligning film formed on one substrate surface. Moreover, it ispreferable for the pixel electrode formed on the one substrate to beconstituted of one substantially rectangular transparentelectroconductive film having an area corresponding to the pixel.

According to a third aspect of the present invention, there is provideda liquid crystal display apparatus a liquid crystal display apparatuscomprising:

a pair of substrates arranged to face each other with a predeterminedgap therebetween;

a liquid crystal layer which is disposed in the gap between the pair ofsubstrates with long axes of liquid crystal molecules being aligned in apredetermined direction, in substantially parallel with substratesurfaces;

a plurality of thin film transistors which are arranged in a rowdirection and a column direction on an inner surface side of one of thepair of substrates that faces the other substrate, and to which displaysignals corresponding to display data are supplied;

a plurality of pixel electrodes which are provided on the inner surfaceside of the one substrate to be electrically connected with the tin filmtransistors, and to which the display signals are supplied from the thinfilm transistors;

a plurality of scanning lines which are respectively arranged betweenrespective pixel electrode rows along the row direction on the innersurface side of the one substrate and which supply scanning signals tothe thin film transistors in the respective rows;

a plurality of signal lines which are respectively arranged betweenrespective pixel electrode columns along the column direction on theinner surface side of the one substrate and which supply display signalsto the thin film transistors in the respective columns;

a common electrode which is constituted of a transparentelectroconductive film which is formed to correspond to the pixelelectrode on the liquid crystal display side apart from the pixelelectrode through an insulating film and in which a plurality of edgeportions aligned in parallel with each other at intervals in a regioncorresponding to each pixel are formed, and a metal electroconductivefilm which is formed along both the scanning line extending in the rowdirection between pixels adjacent to each other and the signal lineextending in the column direction between the same at a part excluding aregion corresponding to the thin film transistor to cover the scanningline and the signal line on the inner surface side of the one substrate,the common electrode generating an electric field which controls analignment direction of the liquid crystal molecules in a planesubstantially parallel with the substrate surfaces between itself andthe pixel electrode; and

a light shielding film which is formed in a region corresponding to thethin film transistor formed on one substrate on an inner surface side ofthe other one of the pair of substrates.

In the liquid crystal display apparatus according to the first aspect ofthe present invention, the common electrode is superimposed to cover thepixel electrode through the insulating film on the liquid crystal layerside apart from the pixel electrode, at least one edge portion is formedin accordance with each region corresponding to the pixel electrode, andan electric field which controls an alignment direction of the liquidcrystal molecules in a plane substantially parallel with the substratesurface is generated between the pixel electrode and the edge portion.Therefore, an electric field which is generated in a peripheral portionof the pixel electrode excluding a part between the pixel electrode andthe common electrode is blocked off with respect to the liquid crystallayer, and hence disorder of alignment of the pixel peripheral portioncan be eliminated, thereby avoiding light leak.

In this liquid crystal display apparatus, it is desirable to form in thecommon electrode a plurality of slits which form edges facing the pixelelectrode in accordance with the regions corresponding to the pluralityof pixel electrodes. Adopting such a structure can generate an electricfield having a substantially uniform intensity between each edge portionof the common electrode and the pixel electrodes, thereby displaying ahigh-quality image.

Additionally, in this liquid crystal display apparatus, a plurality ofscanning lines which are respectively formed along each pixel electroderow and supply gate signals to the thin film transistors in therespective rows and a plurality of signal Lines which are respectivelyformed along each pixel electrode column and supply data signals to thethin film transistors in the respective columns are provided on theinner surface of one electrode, the common electrode is formed on aninsulating layer covering the plurality of pixel electrodes, thin filmtransistors, scanning lines and signal lines into a shape extending inat least one of the pixel electrode row direction and the pixelelectrode column direction by a region covering at least one of a regionbetween the pixel electrodes adjacent to each other with the scanningline therebetween and a region between the pixel electrodes adjacent toeach other with the signal line therebetween, a part of the commonelectrode corresponding to the pixel electrode is constituted of aplurality of partial electrodes aligned in parallel with each other atintervals, and an electric field which controls an alignment directionof the liquid crystal molecules is generated between an edge portion ofeach partial electrode and the pixel electrode. Therefore, an electricfield generated between at least one of the scanning line and the signalline and the edge portion of the pixel electrode can be blocked off bythe common electrode, and disorder of alignment of the liquid crystalmolecules in a region around each pixel due to the electric field can beeliminated. Therefore, light leak in the pixel peripheral portion can beeliminated, thereby display a high-quality image having high contrastand a high numerical aperture.

In this liquid crystal display apparatus, the common electrode is formedto correspond to both a region between the pixel electrodes adjacent toeach other with the plurality of scanning lines therebetween and aregion between the pixel electrodes adjacent to each other with thesignal line therebetween, and it is formed of the electroconductive filmin which a plurality of slits forming a plurality of partial electrodesaligned in parallel at intervals in each part corresponding to each ofthe plurality of pixel electrodes. Therefore, light leak can beeliminated on an entire circumference of the pixel peripheral portion,the plurality of partial electrodes of the common electrodecorresponding to the pixel electrode and portions of the commonelectrode corresponding to the regions between the pixel electrodesadjacent to each other can have substantially equal potentials, and anelectric field having a substantially uniform intensity can be generatedbetween the respective edge portions of the common electrode and thepixel electrodes, thereby displaying a high-quality image.

Further, it is desirable to form the plurality of pixel electrodes intoa shape corresponding to a predetermined entire pixel region. Adoptingsuch a configuration can substantially homogenize potentials of thepixel electrodes as a whole and generate an electric field having asubstantially uniform intensity between the edge portions of the commonelectrode and the pixel electrodes, thereby displaying a higher-qualityimage.

Furthermore, in this liquid crystal display apparatus, a commonelectrode line formed of a metal electroconductive film having a lowresistance is provided at a part of the common electrode correspondingto a region between the pixel electrodes along an entire length of thisregion along the scanning lines and the signal lines. As a result, thecommon electrode of the plurality of pixels arranged in the rowdirection and the column direction can have a substantially equalpotential, thereby displaying an image having no luminanceirregularities.

In the liquid crystal display apparatus according to the second aspectof the present invention, the common electrode is constituted of: thetransparent electroconductive film which is formed to correspond to thepixel electrode through the insulating film on the liquid crystal layerside apart from the pixel electrodes and on which a plurality of edgeportions aligned in parallel with each other at intervals in a regioncorresponding to each pixel are formed; and the metal electroconductivefilm which is formed along at least the scanning line of the scanningline extending in the row direction between the pixels adjacent to eachother and the signal line extending in the column direction between thesame to cover the scanning line and the thin film transistor.Furthermore, an electric field which controls an alignment direction ofthe liquid crystal molecules in a plane substantially parallel with thesubstrate surface is generated between the control electrode and thepixel electrode. Therefore, an electric field generated in a peripheralportion of the pixel electrode other than a part between the pixelelectrode and the common electrode is blocked off with respect to theliquid crystal layer. As a result, light leak can be avoided withoutdisorder of alignment in the pixel peripheral portion, thereby effectingbright display having high contrast and a high numerical aperture.Moreover, since the metal electroconductive film is formed on the commonelectrode along both the scanning line and the signal line, anelectrical resistance of the common electrode can be decreased, and theuniform electrode can be applied to each pixel. Additionally, since themetal electroconductive film is formed to correspond to each thin filmtransistor, light shielding of this thin film transistor can beperformed, thereby carrying out stable display.

In this liquid crystal display, when the V-shaped slits are provided inthe common electrode, behaviors of the liquid crystal molecules due toapplication of an electric field can be stabilized. Further, when thepixel electrode is formed of one rectangular transparentelectroconductive film, manufacture can be facilitated, therebyhomogenizing an electric field of each pixel.

In the liquid crystal display apparatus according to the third aspect ofthe present invention, the common electrode is constituted of: thetransparent electroconductive film which is formed to correspond to thepixel electrode through the insulating film on the liquid crystal layerside apart from the pixel electrode and in which the plurality of edgeportions aligned in parallel with each other at intervals in a regioncorresponding to each pixel are formed; and the metal electroconductivefilm which is formed along both the scanning line extending in the rowdirection between the pixels adjacent to each other and the signal lineextending in the column direction between the same to cover the scanningline and the signal line in a part excluding the region corresponding tothe thin film transistor. Furthermore, an electric field which controlsan alignment direction of the liquid crystal molecules in a planesubstantially parallel with the substrate surface is generated betweenthe common electrode and the pixel electrode. Therefore, an electricfield which is generated in a peripheral part of the pixel electrodeother than a part between the pixel electrode and the common electrodeis blocked off with respect to the liquid crystal layer. As a result,light leak can be avoided without disorder of alignment in the pixelperipheral portion, thereby effecting bright display having highcontrast and a high numerical apertures. Moreover, since the metalelectroconductive film is formed on the common electrode along both thescanning line and the signal line, an electrical resistance of thecommon electrode can be reduced, and a uniform electrode can be appliedto each pixel. Additionally, the metal electroconductive film is formedon the part excluding the region corresponding to the thin filmtransistor, and the light shielding film is formed on the inner surfaceof the other substrate in the region corresponding to the thin filmtransistor. Therefore, a stray capacity generated between this thin filmtransistor and the common electrode can be reduced so that a loadapplied to a driver of this liquid crystal display apparatus can bedecreased.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a plan view showing a part of a liquid crystal displayapparatus according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a cross-sectional view taken along a line III-III in FIG. 1;

FIG. 4 is a cross-sectional view taken along a line IV-IV in FIG. 1;

FIG. 5 is a plan view showing a part of a liquid crystal displayapparatus according to a second embodiment of the present invention;

FIG. 6 is a cross-sectional view taken along a line VI-VI in FIG. 5;

FIG. 7 is a plan view showing a part of a liquid crystal displayapparatus according to a third embodiment of the present invention;

FIG. 8 is a cross-sectional view taken along a line VIII-VIII in FIG. 7;

FIG. 9 is a cross-sectional view taken along a line IX-IX in FIG. 7;

FIG. 10 is a plan view showing a part of a liquid crystal displayapparatus according to a fourth embodiment of the present invention;

FIG. 11 is a cross-sectional view taken along a line XI-XI in FIG. 10;

FIG. 12 is a plan view showing a part of a liquid crystal displayapparatus according to a fifth embodiment of the present invention; and

FIG. 13 is a cross-sectional view showing a part of a liquid crystaldisplay apparatus according to a sixth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

FIGS. 1 to 4 show a first embodiment of the present invention, in whichFIG. 1 is a plan view showing a part of a liquid crystal displayapparatus, FIG. 2 is a cross-sectional view taken along a line II-II inFIG. 1, FIG. 3 is a cross-sectional view taken along a line III-III inFIG. 1 and FIG. 4 is a cross-sectional view taken along a line IV-IV inFIG. 1.

This liquid crystal display apparatus is an active matrix liquid crystaldisplay apparatus, and a liquid crystal layer 3 in which liquid crystalmolecules are aligned in substantially parallel with surfaces of a pairof transparent substrates 1 and 2 facing each other with a gaptherebetween with long axes being aligned in one direction is disposedbetween the substrates 1 and 2 as shown in FIGS. 1 to 4. On one ofopposed inner surfaces of the pair of substrates 1 and 2, i.e., an innersurface of the one substrate, e.g., the substrate 2 on the opposite sideof a display observation side (an upper side in FIGS. 2 and 3), thereare provided follow members. A plurality of transparent pixel electrodes4 which are arranged in a row direction (a lateral direction in FIG. 1)and a column direction (a vertical direction in FIG. 1). A plurality ofthin film transistors (which will be referred to as TFTs hereinafter) 5are respectively connected with these pixel electrodes 4. A plurality ofscanning lines 12 are respectively formed along one side of each pixelelectrode row and supply gate signals to the TFTs 5 in the respectiverows. A plurality of signal lines 13 are respectively formed along oneside of each pixel electrode column and supply data signals to the TFTs5 in the respective columns. Finally, a transparent common electrode 15is superimposed on the liquid crystal layer 3 side of the plurality ofpixel electrodes 4 to cover the pixel electrodes 4 through an insulatingfilm 14, at least one edge portion 15 d being formed in accordance witha region corresponding to the pixel electrode 4. The common electrode 15generates an electric field between the pixel electrode 4 and the edgeportion 15 d. The electric field controls an alignment direction of theliquid crystal molecules of the liquid crystal layer 3 in a placesubstantially parallel with the surfaces of the substrates 1 and 2.

Respective rim portions of the pair of substrates 1 and 2 are bondedthrough a non-illustrated frame-like sealing material. The liquidcrystal layer 3 is formed by sealing a nematic liquid crystal having apositive dielectric anisotropy in a region surrounded by the sealingmaterial between the substrates 1 and 2.

The TFT 5 is constituted as follows, gate electrode 6 is formed on anupper surface of the substrate 2, a transparent gate insulating film 7is formed on a substantially entire upper surface of the substrate 2 tocover the gate electrode 6. An i-type doped semiconductor film 8 isformed on this gate insulating film 7 to face the gate electrode 6. Asource electrode 10 and a drain electrode 11 are respectively providedon both side portions of the i-type semiconductor film 8 with a channelregion therebetween through an n-type semiconductor film 9.

The plurality of scanning lines 12 are formed on the upper surface ofthe substrate 2 to be electrically connected with the gate electrodes 6of the TFTs 5, and the plurality of signal lines 13 are formed on thegate insulating film 7 to be electrically connected with the drainelectrodes of TFTs 5.

Each of the plurality of pixel electrodes 4 is formed into asubstantially rectangular shape which corresponds to an entirepredetermined pixel region on the gate insulating film 7 by using atransparent electroconductive film such as an ITO film. The sourceelectrode 10 of the TFT 5 corresponding to each pixel electrode 4 iselectrically connected with one corner portion of this pixel electrode4.

The transparent interlayer insulating film 14 which covers the pluralityof pixel electrodes 4, TFTs 5, scanning lines 12 and signal lines 13 isformed on the substantially entire inner surface side of the substrate2. The common electrode 15 is formed on an insulating layer constitutedof the gate insulating film 7 and the interlayer insulating film 14 tocover the pixel electrodes 4.

The common electrode 15 is formed of one transparent electroconductivefilm such as an ITO film. This common electrode is formed to correspondto not only the upper side of the pixel electrodes 4 but also both aregion between the pixel electrodes 4 adjacent each other with thescanning line 12 therebetween and a region between the pixel electrodes4 adjacent to each other with the signal line 13 therebetween. Thecommon electrode 15 is constituted of a plurality of elongated partialelectrodes (electrode sections) 15 a extending in parallel with eachother at intervals along the column direction at a part corresponding toeach pixel electrode 4. These electrode sections 15 a are separated fromeach other except both end portions in a lateral direction (the columndirection), by each slit 16 formed between these sub-electrodes 15 a.Each partial electrode 15 a has the edge portions 15 d extending alongeach slit 16 on the slit 16 side.

In this embodiment, the four slits 16 which are parallel to each otheralong the column direction are formed at a part corresponding to each ofthe plurality of pixel electrodes 4 of the transparent electroconductivefilm, and the three partial electrodes 15 a are formed between theseslits.

A width of each of the plurality of partial elongated electrodes 15 aformed at the part of this common electrode 15 corresponding to each ofthe pixel electrodes 4 is set to be equal to a gap between the partialelectrodes 15 a adjacent to each other (a width of the slit 16).

Both side edge parts of a peripheral portion (an elongated portionextending in the column direction) 15 b of the common electrode which ispositioned in a region corresponding to a part of the common electrode15 between the pixel electrodes 4 adjacent to each other with the signalline 13 therebetween are formed to have a width to face each of bothperipheral portions of the pixel electrodes 4 adjacent to each other, asshown in FIG. 2.

Each of the slits 16 is formed to have a length substantially equal to alength of the pixel electrode 4 in the column direction (slightly longeras shown in FIG. 1 in this embodiment). As shown in FIG. 3, in regard toa width of the peripheral portion 15 c of the common electrode (anelongated portion extending in the row direction) between end portionsof the slits 16, which is positioned in a region of the common electrode15 corresponding to a part between the pixel electrodes 4 with theoperation line 12 therebetween, its both side edge parts are formed tohave a width overlapping both peripheral portions of the pixelelectrodes 4 adjacent to each other.

A terminal arrangement portion which laterally extends toward theoutside of the substrate 1 is formed on the substrate 2 in an edgeportion at one end in at least one of the row direction and the columndirection. The plurality of scanning lines 12 and signal lines 13 areelectrically connected with a plurality of scanning line terminals andsignal line terminals arranged and formed on the terminal arrangementportion. The common electrode 15 is electrically connected with a commonelectrode terminal formed on the terminal arrangement portion through alead wiring line led from one or more positions of an outer rim thereof.

A plurality of light shielding films 17 which prevent an erroneousoperation due to light of the TFTs 5 are provided on the inner surfaceof the other substrate 1 to respectively face the plurality of TFTs 5.Further, color filters 18R, 18G and 18B having three colors, i.e., red,green and blue are provided to respectively correspond to each of pixels(regions where an alignment state of the liquid crystal molecules iscontrolled by an electric field generated between the pixel electrodes 4and side edges of the respective partial electrodes 15 a of the commonelectrode 15) formed of the plurality of pixel electrodes 4 and thecommon electrode 15.

Homogeneous alignment films 19 and 20 are respectively provided on theinner surface sides of the substrates 1 and 2 in a region surrounded bythe frame-like sealing material to cover the color filters 18R, 18G and18B and the common electrode 15.

These alignment films 19 and 20 are respectively subjected to analigning treatment when oppositely rubbed along directions obliquelycrossing each other at a predetermined angle in a range of 5° to 15°with respect to an elongated direction of each partial electrode 15 a ofthe common electrode 15. The liquid crystal molecules in the liquidcrystal layer 3, near the alignment films are aligned in substantiallyparallel with the surfaces of the substrates 1 and 2 with long axesbeing aligned in the aligning treatment direction of the correspondingalignment films 19 and 20.

Although not shown, this liquid crystal display apparatus includes apair of polarizing plates respectively arranged on outer side of thepair of substrates 1 and 2. Of these polarizing plates, one polarizingplate is arranged in such a manner that its transmission axis becomessubstantially parallel with the aligning treatment of the alignmentfilms 19 and 20, and the other polarizing plate is arranged in such amanner that its transmission axis becomes substantially perpendicular orparallel with respect to the transmission axis of said one polarizingplate.

In this liquid crystal display apparatus, when a display signal isapplied to each of the plurality of pixel electrodes 4 through each TFT5, an electric field is generated between the edge portion of eachpartial electrode 15 a of the common electrode 15 and the part of thepixel electrode 4 corresponding to the portion between the partialelectrodes 15 a, and an alignment direction of the liquid crystalmolecules is controlled by this electric field in a plane substantiallywith the surfaces of the substrates 1 and 2, thereby effecting display.

In this liquid crystal display apparatus, the common electrode 15 issuperimposed to cover the pixel electrodes 4 through the insulating film(the interlayer insulating film) 14 on the liquid crystal layer 3 sideapart from the pixel electrodes 4, at least one edge portion 15 d isformed in accordance with each region corresponding to each pixelelectrode 4, and an electric field which controls an alignment directionof the liquid crystal molecules in a plane substantially parallel withthe surfaces of the substrates 1 and 2 is generated between the pixelelectrode 4 and the edge portion 15 d. Therefore, an electric filedwhich is generated in the peripheral portion of the pixel electrode 4excluding the part between the pixel electrode 4 and the commonelectrode 15 is blocked off with respect to the liquid crystal layer 3.As a result, light leak can be avoided without disorder of alignment ofthe pixel peripheral portion.

In this liquid crystal display apparatus, the plurality of slits 16which form the edges 15 d facing the pixel electrode 4 are formed in thecommon electrode 15 in accordance with each region corresponding to eachof the plurality of pixel electrodes 4. Thus, an electric field having asubstantially uniform intensity can be generated between each edgeportion 15 d of the common electrode 15 and the pixel electrode 4,thereby displaying a high-quality image.

Further, in the liquid crystal display apparatus, the plurality ofscanning lines 12 which are formed along the respective pixel electroderows and supply the gate signals to the TFTs 5 in the respective rowsand the plurality of signal lines 13 which are formed along therespective pixel electrode columns and supply the data signals to theTFTs 5 in the respective columns are provided on the inner surface ofthe substrate 2. The common electrode 15 is formed into a shapeextending in the pixel electrode row direction and the pixel electrodecolumn direction on the insulating layer (a laminated film formed of thegate insulating film 7 covering the gate electrodes 6 of the TFTs 5 andscanning lines 12, and the interlayer insulating film 14 covering thepixel electrodes 4, the TFTs 5 and the signal lines 13) covering theplurality of pixel electrodes 4, TFTs 5, scanning lines 12 and signallines 13 by the region covering both the region between the pixelelectrodes 4 adjacent to each other with the scanning line 12therebetween and the region between the pixel electrodes 4 adjacent toeach other with the signal line 13 therebetween. The part of the commonelectrode 15 corresponding to the pixel electrode 4 is constituted ofthe plurality of partial electrodes 15 a aligned in parallel with eachother at intervals, and an electric field which controls an alignmentdirection of the liquid crystal molecules is generated between the edgeportion 15 d of each partial electrode 15 a and the pixel electrode 4.Therefore, an electric field generated between the scanning and signallines 12 and 13 and the edge portion of the pixel electrode 4 can beblocked off by the common electrode 15, and disorder of alignment of theliquid crystal molecules at the periphery of each pixel due to thiselectric field can be eliminated. Therefore, light leak between thepixels adjacent to each other can be eliminated, and an image having anexcellent quality can be displayed.

That is, in this liquid crystal display apparatus, the common electrode15 is constituted of the electroconductive film which is formed tocorrespond to both the region between the pixel electrodes 4 adjacent toeach other with the scanning line 12 therebetween and the region betweenthe pixel electrodes 4 adjacent to each other with the signal line 13therebetween. The plurality of slits 16 forming the plurality of partialelectrodes 15 a aligned in parallel at intervals are provided at theparts of the electroconductive film corresponding to the plurality ofpixel electrodes 4. Therefore, it is possible to block off both anelectric field generated between the scanning line 12 and the edgeportion of the pixel electrode 4 and an electric field generated betweenthe signal line 13 and the edge portion of the pixel electrode 4 by theportions 15 b and 15 c of the common electrode 15 corresponding to theregions between the pixel electrodes 4 adjacent to each other.

Accordingly, an electric field generated between the scanning line 12and the edge portion of the pixel electrode 4 and an electric fieldgenerated between the signal line 13 and the edge portion of the pixelelectrode 4 do not affect the liquid crystal layer 3, and alignment ofthe liquid crystal molecules in the regions between the pixels adjacentto each other is not disordered. Therefore, light leak can be eliminatedin the entire pixel peripheral portion.

Further, according to this liquid crystal display apparatus, the commonelectrode 15 is formed of the electroconductive film having theplurality of slits 16 forming the plurality of partial electrodes 15 aprovided at the parts corresponding to the plurality of pixel electrodes4. Therefore, the plurality of partial electrodes 15 a corresponding tothe pixel electrode 4 and the portions 15 b and 15 c corresponding tothe regions between the pixel electrodes 4 adjacent to each other in thecommon electrode 15 can have a substantially equal potential, and anelectric filed having a substantially uniform intensity can be generatedbetween the edge portion of each partial electrode 15 a of the commonelectrode 15 and the part of the pixel electrode 4 corresponding to thepart between the partial electrodes 15 a, thereby uniformly controllingthe alignment direction of the liquid crystal molecules in the entireregion of the pixels.

Therefore, in this liquid crystal display apparatus, there is no lightleak in both the part between the adjacent pixels with the scanning line12 therebetween and the part between the adjacent pixels with the signalline 13 therebetween. Therefore, a black mask which blocks off leaklight around each pixel does not have to be provided, and an apertureratio can be increased, thereby displaying a bright image with highcontrast. Furthermore, since the pixel electrodes 4 are arranged to becloser to the substrate side as compared with the common electrode 15, athrough hole or the like does not have to be provided to achieveconnection with the source electrode of each TFT 5. Therefore, amanufacturing process becomes simple, and a reduction in an apertureratio due to the through hole does not occur. Moreover, since the commonelectrode 15 is formed in a state where it is electrically connectedwith the substantially entire surface of the substrate, a high-qualityimage can be displayed with a uniform light transmission factor of eachpixel on the entire region of the pixels.

Additionally, according to this liquid crystal display apparatus, sincethe plurality of pixel electrodes 4 are formed into shapes correspondingto the predetermined entire pixel region, the pixel electrodes 4 canhave potentials which are substantially equal on the whole, an electricfield having a further uniform intensity can be generated between theedge portion of each partial electrode 15 a of the common electrode 15and the portion of the pixel electrode 4 corresponding to the partbetween the partial electrodes 15 a, and the alignment direction of theliquid crystal molecules can be further uniformly controlled in theentire region of the pixels, thereby displaying an image with a higherquality.

Second Embodiment

FIGS. 5 and 6 show a second embodiment of the present invention, inwhich FIG. 5 is a plan view showing a part of a liquid crystal displayapparatus and FIG. 6 is a cross-sectional view taken along a line VI-VIin FIG. 5.

In the liquid crystal display apparatus according to this embodiment, acommon electrode line 21 constituted of a metal electroconductive filmhaving a low resistance is provided at a portion of the common electrode15 corresponding to a region between the pixel electrodes 4 along anentire length of this region, and other structures are the same as thosein the first embodiment. Therefore, like reference numerals denotemembers equal to those in the first embodiment, thereby eliminatingtheir explanation.

Each common electrode line 21 is formed on the interlayer insulatingfilm 14 in parallel with the scanning or line at a position overlappingthe scanning or line to correspond to one of a region between theadjacent pixel electrodes 4 with the scanning line 12 therebetween, anda region between the adjacent pixel electrodes 4 with the signal line 13therebetween. In this embodiment, the common electrode lines is providedin the region between the adjacent pixel electrodes 4 with the signalline 13 therebetween. The common electrode lines 21 are connected incommon on the outer side of an arrangement region of the pixelelectrodes 4, and its common connecting portion is connected with acommon electrode terminal formed at a terminal arrangement portion ofthe substrate 2.

Additionally, the common electrode 15 is formed on the interlayerinsulating film 14 to overlap the common electrode lines 21.

In this liquid crystal display apparatus according to this embodiment,each common electrode line 21 formed of the metal electroconductive filmhaving a low resistance is provided at the part of the common electrode15 corresponding to the region between the pixel electrodes 4 along theentire length of this region. Therefore, a potential of the commonelectrode 15 of the plurality of pixels arranged in the row directionand column directions can be substantially homogenized, therebydisplaying an image without luminance irregularities.

In this embodiment, each common electrode line 21 is provided at thepart of the common electrode 15 corresponding to the region between thepixel electrodes 4 adjacent to each other with the signal line 13therebetween. However, the common electrode line 21 may be provided at apart corresponding to the region between the pixel electrodes 4 adjacentto each other with the scanning line 12 therebetween. Further, thecommon electrode line 21 may be provided on the common electrode 15.

In the first and second embodiments, the common electrode 15 is formedto correspond to the plurality of pixel electrodes 4 and both the regionbetween the pixel electrodes 4 adjacent to each other with the scanningline 12 therebetween and the region between the pixel electrodes 4adjacent to each other with the signal line 13 therebetween. However,the common electrode 15 may be formed to correspond to the plurality ofpixel electrodes 4 and one of the region between the adjacent pixelelectrodes 4 with the scanning line 12 therebetween and the regionbetween the adjacent pixel electrodes 4 with the signal line 13therebetween.

In this case, an electric field generated between at least one of thescanning line 12 and the signal line 13 and the edge portion of thepixel electrode 4 can be blocked off by the common electrode 15 so thatdisorder of alignment of the liquid crystal molecules in the regionbetween the adjacent pixels due to this electric field can beeliminated. Therefore, light leak between the pixels adjacent to eachother can be eliminated, thereby displaying an image with an excellentquality.

When the common electrode 15 is formed to correspond to the plurality ofpixel electrodes 4 and one of the region between the adjacent pixelelectrodes 4 with the scanning line 12 therebetween and the regionbetween the adjacent pixel electrodes 4 with the signal line 13therebetween in this manner, it is good enough to form the commonelectrode 15 of the electroconductive film which is formed to correspondto the plurality of pixel electrodes 4 and the regions between the pixelelectrodes 4 in accordance with each pixel row or each pixel column, theelectroconductive film being constituted of a plurality of partialelectrode segment to which a plurality of slits or comb-like elongatednotch portions forming a plurality of partial electrodes 15 a aligned inparallel at intervals are provided at parts corresponding to theplurality of pixel electrodes 4, and a connecting portion which connectsend portions of these partial electrodes in common.

Third Embodiment

FIGS. 7, 8 and 9 show a third embodiment of the present invention, inwhich FIG. 7 is a plan view showing a part of a liquid crystal displayapparatus, FIG. 8 is a cross-sectional view taken along a line VIII-VIIIin FIG. 7 and FIG. 9 is a cross-sectional view taken along a line IX-IXin FIG. 7.

In the liquid crystal display apparatus according to this embodiment,common electrode lines formed of a metal electroconductive film having alow resistance are formed in a reticular or grid pattern to correspondto both regions each positioned between adjacent pixel electrodes 4 withthe signal line 13 therebetween and regions each provided between theadjacent pixel electrodes 4 with the scanning line 12 therebetween inaddition to partial electrodes 15 a. Other structures are the same asthose in the second embodiment. Therefore, like reference numeralsdenote members equal to those in the second embodiment, therebyeliminating their explanation.

In this liquid crystal display apparatus, the common electrode line 121constituted of the metal electroconductive film having a low resistanceis formed on the interlayer insulating film 14. The common electrodeline 121 as a grid-like shape includes a column wiring line portion 121a extending in parallel with the signal line 13 at a positionoverlapping the signal line 13 a row wiring line portion 121 belectrically connected to the column wiring line portion 121 a. Thelather portion 121 b extends in parallel with the scanning line 12 at aposition overlapping the scanning line 12 between the adjacent pixelelectrodes 4 with the scanning line 12 therebetween. That is, the gridscommon electrode line 121 is formed to surround all four outer sides ofthe pixel electrodes 4 by the column wiring line portions 121 a and thecolumn wiring line portions 121 b. Furthermore, a part of the row wiringline portion 121 b corresponding to the TFT 5 is widely formed withrespect to the other portion of row wiring line portion 121 b, therebyforming a light shielding portion 121 c which covers the upper side ofthe TFT 5.

The common electrode 15 is formed to be superimposed on the interlayerinsulating film 14 and the common electrode line or grid film 121.

Also, in this liquid crystal display apparatus, the common electrode 15is constituted of a transparent electroconductive film in which aplurality of edge portions 15 d aligned in parallel with each other atintervals in a region corresponding to each pixel are formed, and ametal electroconductive film formed along both the scanning line 12extending in the row direction between the adjacent pixels and thesignal line 13 extending in the column direction on the insulating film14 of the substrate 2.

According to the liquid crystal display apparatus of this embodiment,the parts of the common electrode line 121 extending along the scanningline 12 and the signal line 13 are provided at the portion of the commonelectrode 15 corresponding to the regions between the pixel electrodes 4adjacent to each other. Therefore, a potential of the common electrode15 of the plurality of pixels arranged in the row and column directionscan be substantially homogenized, thereby displaying an image withoutluminance irregularities. Moreover, since the light shielding portion121 c is formed in the row wiring line portion 121 b formed along thescanning line 13, the semiconductor layer of the TFT 5 can be shieldagainst light. Therefore, a light shielding film does not have to formedon the substrate on the opposed observation side, thus increasing anumerical apertures.

Fourth Embodiment

FIGS. 10 and 11 show a fourth embodiment of the present invention, inwhich FIG. 10 is a plan view showing a part of a liquid crystal displayapparatus, and FIG. 11 is a cross-sectional view taken along a lineXI-XI in FIG. 10.

In the liquid crystal display apparatus according to this embodiment, acommon electrode line or layer formed of a metal electroconductive filmhaving a low resistance is formed in a reticular grid pattern tocorrespond to both regions between the adjacent pixel electrodes 4 withthe signal lines 13 therebetween and regions between the adjacent pixelelectrodes 4 with the scanning lines 12 therebetween except regionscorresponding to TFTs 5, and a light shielding film is formed in regionsof the opposed substrate 1 facing the TFTs 5. Other structures are thesame as those in the third embodiment. Therefore, like referencenumerals denote members equal to those in the third embodiment, therebyeliminating their explanation.

In this liquid crystal display apparatus, a common electrode lines 221formed of the metal electroconductive film having a low resistance isformed into a shape in which a column wiring line portion 221 aextending in parallel with the signal line 13 at a position overlappingthe signal line 13 is connected with a row wiring line portion 221 bextending in parallel with the scanning line 12 at a positionoverlapping the scanning line 12 to correspond both the region betweenthe adjacent pixel electrodes 4 with the scanning line 12 therebetweenand the region between the adjacent pixel electrodes 4 with the signalline 13 therebetween on the interlayer insulating film 14. That is, thiscommon electrode layer 221 is formed into a reticular pattern whichsurrounds all four outer sides of the pixel electrodes 4 by the columnwiring line portions 221 a and the row wiring line portions 221 b. Awide portion 221 c is formed in the row wiring line portion 221 b of thecommon electrode line 221 formed in parallel with the scanning lien 12in a region corresponding to the TFT 5, and an opening 221 d is formedin a part of this wide portion 221 c corresponding to the TFT 5.

A transparent electroconductive film of the common electrode 15 isformed to be superimposed on the interlayer insulating film 14 and thecommon electrode line 22 except the openings 221 d of the row wiringline portion 221 b. Therefore, the common electrode 15 formed of thetransparent electroconductive film and the metal electroconductive filmis formed in a region excluding the upper side of each TFT 5.

A light shielding film 217 is provided in a region corresponding to eachTFT 5, on an inner surface of the second substrate 1 as an observationside facing the first substrate 2.

As described above, in this liquid crystal display apparatus, the commonelectrode 15 formed of the transparent electroconductive film and themetal electroconduction film, the transparent film being formed tocorrespond pixel electrodes 4 on the liquid crystal layer 3 side apartfrom each pixel electrodes 4 through the insulating film 14 and in whicha plurality of edge portions aligned in parallel with each other atintervals in regions corresponding to pixels, and the metal film beingformed along both the scanning lines 12 extending in the row directionbetween the pixels adjacent to each other and the signal lines 13extending in the column direction in regions corresponding to the TFTs 5to cover these scanning lines 12 and signal lines 13. Furthermore, thelight shielding film 217 is arranged in the region corresponding to eachTFT 5.

According to the liquid crystal display apparatus of this embodiment,the common electrode line 221 formed of the metal electroconductive filmhaving a low resistance is provided at portions of the common electrode15 corresponding to the regions between the pixel electrodes 4 adjacentto each other along the scanning lines 12 and the signal lines 13.Therefore, a potential of the common electrode 15 of the plurality ofpixels arranged in the row direction and the column direction can besubstantially homogenized, thereby displaying an image without luminanceirregularities. Moreover, since the common electrode 15 formed of thetransparent electroconductive film and the metal electroconductive filmis formed in the regions excluding the upper sides of TFTs 5, a straycapacity formed between the common electrode 15 and the TFTs 5 can bereduced, and a load applied to a driver of the liquid crystal displayapparatus can be decreased. Additionally, just forming the lightshielding film 217 which shields each TFT 5 alone against light on thesecond substrate 1 can suffice, thus increasing a aperture ratio of eachpixel.

Fifth Embodiment

The description has been given as to the example in which each slit isformed in parallel with the signal line 13 and each partial electrode 15a is provided in parallel with the signal line 13 in the commonelectrode 15 in conjunction with the first to fourth embodiments.However, the liquid crystal display apparatus according to the presentinvention is not restricted thereto, and each slit may be obliquelyformed with respect to the signal line 13 as shown in FIG. 12.

FIG. 12 shows a liquid crystal display apparatus according to the fifthembodiment of the present invention, and it is a plan view showing aplanar shape of a common electrode formed on a first substrate when astructure of the common electrode according to this embodiment isapplied to the third embodiment. This fifth embodiment is different fromthe third embodiment in a shape of the common electrode alone, and otherstructures are the same. Therefore, like reference numerals denote likemembers, thereby eliminating their explanation.

As shown in FIG. 12, each slit 116 formed in a common electrode 115 isformed in a direction obliquely crossing an aligning treatment direction20 a of an alignment film 20 to form each edge portion 115 d whichcrosses in an oblique state except perpendicular and parallel states adirection of long axes of liquid crystal molecules aligned by thealignment film 20 formed on an inner surface of the substrate 2. Thatis, in the common electrode 115 according to this embodiment, the slits116 forming the plurality of edge portions 115 d aligned in parallelwith each other at intervals are provided, and these slits are bent in aV-like shape to form the edge portions which cross in an oblique stateexcept perpendicular and parallel states the aligning treatmentdirection 20 a indicated by an arrow of the alignment film 20 formed onthe inner surface of the substrate 2.

According to this configuration, when a voltage is applied between eachpixel electrode 4 and the common electrode 115 with respect to liquidcrystal molecules initially aligned between the pair of substrates, anelectric field in an oblique direction is applied to the liquid crystalmolecules. Therefore, behaviors of the liquid crystal molecules can beuniformed, thereby avoiding disorder of alignment of the liquid crystalmolecules in each pixel.

It is to be noted that the shape of this common electrode can be appliedeach of the first to fourth embodiments.

Sixth Embodiment

Although each of the plurality of pixel electrodes 4 is formed into asubstantially rectangular shape corresponding to a predetermined entirepixel region, in the first to fifth embodiments, the pixel electrode 4may be formed into a comb-like shape corresponding to regions betweenthe plurality of partial electrodes 15 a of the common electrode 15.

The pixel electrode is formed into a comb-like shape in the sixthembodiment, and FIG. 13 shows an example in which this pixel electrodeconfiguration is applied to the liquid crystal display apparatusaccording to the third embodiment. The sixth embodiment is differentfrom the third embodiment in a shape of the pixel electrode alone, andother structures are the same. Therefore, like reference numerals denotelike members, thereby eliminating their explanation.

As shown in FIG. 13, in the pixel electrode configuration according tothis embodiment, a plurality of opening portions 104 b are formed ineach pixel electrode 104 to form a plurality of pixel partial electrodes104 a. This opening portion 104 b has a shape corresponding to a slit 16formed in the common electrode 15 in a region corresponding to thispixel electrode 104, and it is formed in a region overlapping the slit16 of the common electrode 15.

Further, it is desirable to form both side edges of a part of this pixelelectrode 104 corresponding to a region between the partial electrodes104 a to have widths respectively facing edge portions of the partialelectrodes 15 a adjacent to each other in the common electrode 15.

Such a shape of the common electrode also, can be applied to each of thefirst to fifth embodiments.

According to this pixel electrode 104, since a total area overlappingthe common electrode 15 is reduced, a stray capacity generated betweenthe pixel electrode 104 and the common electrode 15 can be reduced,thereby decreasing a load applied to a driver of the liquid crystaldisplay apparatus.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventionconcept as defined by the appended claims and their equivalents.

1. A liquid crystal display device comprising: a first substrate; asecond substrate which is arranged to face the first substrate; a liquidcrystal layer which is provided between the first substrate and thesecond substrate; a thin film transistor which is formed on a surfaceside of the second substrate facing the first substrate; a pixelelectrode which is formed on the surface side of the second substratefacing the first substrate, and which is connected to the thin filmtransistor; a scanning line which supplies a gate signal to the thinfilm transistor; a signal line which supplies a data signal to the thinfilm transistor; an insulating film which covers the thin filmtransistor, the pixel electrode, the scanning line, and the signal line;and a common electrode which is arranged on the insulating film, whereinthe pixel electrode has a pair of first short side edges extending in afirst direction, and a pair of first long side edges extending a seconddirection perpendicular to the first direction, and wherein the commonelectrode has a plurality of first slits in a portion overlapping withthe pixel electrode, the first slits having a pair of second short sideedges which extend in the first direction and which are shorter than thepair of the first short side edges, and a pair of second long side edgeswhich extend in the second direction and which are longer than the pairof the first long side edges such that the pair of the second short sideedges are arranged so as to be not overlapped with the pixel electrode.2. The liquid crystal display device according to claim 1, wherein saidpair of the second long side edges extend in a direction perpendicularto a direction in which the scanning line extends.
 3. The liquid crystaldisplay device according to claim 1, wherein said pair of the secondlong side edges extend in a direction in which the signal line extends.4. The liquid crystal display device according to claim 1, furthercomprising an alignment film which is formed on the common electrode andwhich initially aligns liquid crystal molecules in the liquid crystallayer in an oblique direction with respect to the second long sideedges.
 5. The liquid crystal display device according to claim 1,wherein the common electrode includes: a transparent electroconductivefilm which is formed on the insulating film, and which has said firstslits, and a metal electroconductive film which is provided between thetransparent electroconductive film and the insulating film, and whichcovers the scanning line and the signal line.
 6. The liquid crystaldisplay device according to claim 1, wherein the liquid crystal layerincludes liquid crystal molecules which have a positive dielectricanisotropy, and which are aligned so that long axes of the liquidcrystal molecules are substantially parallel with surfaces of the firstand second substrates.
 7. The liquid crystal display device according toclaim 5, wherein the metal electroconductive film defines a plurality ofsecond slits in each of which the first slits of the transparentelectroconductive film and the pixel electrode are overlapped.